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    <title>Document</title>
    <script type="text/javascript">
    // 1.将A5F3转成2进制
           var mu ='A5F3'
        var mu2 = parseInt(mu,16)
        var zh =mu2.toString(2)
        console.log(zh);    

//2.99乘法
      
    for (let i = 1; i <=9; i++) {    
        for (let x = 1; x <= i; x++) {
           
        document.write(x + '*' + i + '=' + i*x + ' ');
        }
        document.write('<br>')
    }



  //  3.输入年月，（用数组）
  //    3.1.计算当月有多少天

  if(arr[1]==1|arr[1]==3|arr[1]==5|arr[1]==7|arr[1]==8|arr[1]==10|arr[1]==12){

        document.write('当月有'+31+'天')
}else if(arr[1]==4|arr[1]==6|arr[1]==9|arr[1]==11){

        document.write('当月有'+30+'天')
}else if (arr[1]==2){

        if(arr[0]%4==0&&arr[0]%100!=0)

        document.write('当月有'+29+'天')
}else{
        document.write('当月有'+28+'天')
}




   //   3.2.计算还剩多少天
   document.write('<br>')
if(arr[1]==1|arr[1]==3|arr[1]==5|arr[1]==7|arr[1]==8|arr[1]==10|arr[1]==12){
   var a=31
   a=a-parseInt(arr[2]) 
    document.write('当月还有'+a+'天')
}else if(arr[1]==4|arr[1]==6|arr[1]==9|arr[1]==9|arr[1]==11){
    var b=30
    b=b-parseInt(arr[2]) 
    document.write('当月还有'+b+'天')
}
else if (arr[1]==2){
    var c=28
if(arr[0]%4==0&&arr[0]%100!=0)

    document.write('当月还有'+((c+1)-parseInt(arr[2]) )+'天')
}else{
    document.write('当月还有'+c+'天')
}


    </script>
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